Patent Application
20050189092
The present invention relates to housings (1), preferably according to
Known turbulence elements or turbulence generators are manufactured from wires or thin rods with a circular cross-section and sold for example by the CalGavin company via its internet home page http://www.calgavin.co.uk/HITRAN/hitran.htm (of Nov. 15, 2002) under the name HITRAN® Thermal System. The circular wire used in this system only produces a slight improvement in the heat transfer performance at high flow rates. The circular cross-sections of the wire do not however provide sufficient improvement in the intense mixing effect required for increased performance. At high flow rates, such as for example in the case of aqueous or gaseous systems, turbulent flow is usually enhanced. It is known from the science of fluid dynamics that inserts with circular cross-sections produce only a low degree of transverse flow and that this mixing transverse flow disappears almost completely even at only low viscosities (of a few mPa·s) of the fluid.
It is for this reason that turbulence elements or turbulence generators are only known in relation to aqueous systems. EP 0 623 771 B1 suggests solving this problem by soldering wires having complicated undulations into flat tubes, shaped tubes or tubular bodies to act as turbulence elements. In this variant, low heat conduction into the primary region of flow occurs due to the metallic contact between the heat transfer tube and the bent wire.
CH 627 263 A5 (=U.S. Pat. No. 4,211,277) describes a flow passage provided with fittings for a medium involved in indirect exchange, and in particular heat exchange, wherein the fittings consist of at least two groups of webs, the webs within each group are aligned essentially in parallel relation and in angular relation to the axis of the passage, the webs of the one group cross the webs of the other group and at least some of the webs are connected to each other at the crossing points.
CH 648 404 A5(=U.S. Pat. No. 4,352,378) describes a ribbed device assembled from sheet metal elements for improving heat transfer for insertion into tubes of heat exchangers, each sheet metal element having teeth which fit into the teeth of the adjacent sheet metal element, the central portions of the sheet metal elements forming a channel.
The above references do not disclose a special design of a housing for adjusting the temperature of liquid and gaseous product streams, into which (housing) at least two insertable, comb-shaped plates are removably inserted which act as turbulence generators on the passage of fluids through the housing.
Static mixers can also be used as turbulence-producing devices. When used industrially, static mixers (from the Kenics, Sulzer and Koch-Glitsch companies) are however frequently too expensive, so that such devices are only rarely used.
Variants are also known in which undulating plates are inserted into shaped ducts and subsequently soldered. These technical solutions do however only provide a slight increase in the size of the product-side heat transfer surface and the performance.
EP-A 0 659 500 discloses flat tubes for improving heat exchange processes which are produced by flat-rolling round tubes. In flat tubes the distance from the temperature-adjusted inner duct wall to the centre of the duct is smaller. The disadvantage of this design is the small temperature-adjusting surface and the low pressure stability of the flat tubes. If products with a higher viscosity are temperature-adjusted in such flat ducts the resulting flow rate distribution is not uniform, thus in turn producing a non-uniform distribution of temperature in the product stream.
Products having a higher viscosity additionally produce high differential pressures, as a result of which flat tubes tend to bulge due to their low pressure stability, and they are not dimensionally stable. High differential pressures in flat tubes also cause them to lose their rectangular cross-section and to revert to a round cross-section. In order to increase the pressure stability of flat tubes the tube wall thickness can be increased, although this has the disadvantage that the heat transfer performance is also reduced.
EP-A 0 302 232 discloses a flat tube for a heat exchanger which can be produced from a bent metal strip. This flat tube can also be provided with turbulence inserts, complete sealing being carried out in a soldering process. Such bent flat metal tubes can only be used for low differential pressures. As soon as the flat tube bends upwards due to high pressure, its improved heat transfer properties disappear. The pressure stability of the flat tube described is increased by incorporating ribs by folding. The ribs change the flat tube in such a manner that a multi-duct flat channel having increased pressure stability is obtained. The resulting individual duct of the flat tube is almost square. This square flow cross-section does however mean that only two temperature-adjusting surfaces are effective. Also the distance from the centre of the duct to the inner temperature-adjusting surface is so great that a temperature gradient forms which prevents uniform, rapid, non-product-damaging temperature adjustment. If a highly viscous product is to be temperature-adjusted at a low, laminar flow rate the temperature differences in the flow cross-section are particularly high.
DE 10 212 799 C1 describes a hollow section which can have inner and outer ribs. The ribs are arranged in the longitudinal direction of the metallic section. The ribs, in particular in the interior of the duct of the section, are very short and do not extend over the entire duct width. For this reason the inner ribs only increase the size of part of the heat-transferring surface and they cannot perform any mixing action or increase turbulence. The hollow section thus described always consists of several parallel quadrangular ducts and additionally has external ribs which are also arranged in a longitudinal direction. All of the inner and outer ribs are used only for increasing the surface area and their design prevents them from performing any mixing functions or increasing turbulence.
DE 3 022 270 C2 (=U.S. Pat. No. 4,352,318) describes rib-like devices (ribbed inserts) for which three or four such plates are always required and the ribs of the plate inserts support each other by interlocking and all of the ribbed inserts have to be inserted jointly into the flow duct and a longitudinal duct (3) is automatically formed along the central axis of the tube due to the middle section (7) of the ribbed inserts and the framework of interlocked plates can be inserted into a flow tube. It is not possible to remove an individual ribbed insert from the flow tube. The ribbed inserts are not turbulence generators but are intended to increase the heat-transferring surface area of the tube and they act as inner heat-transferring ribs, while even reducing the rate of flow in the centre of the tube. As is known, the heat transfer performance does however decrease as the flow rate decreases.
DE 3,022 270 C2 (=U.S. Pat. No. 4,352,318) describes so-called static mixers which are used as pipeline inserts. These static mixers are laboriously assembled from plates or moulded parts and welded together at several contact points of the plates. The welded plates then form three-dimensional mixing elements which are inserted into the tube, several groups of mixers being arranged in succession, each being staggered in relation to the next by an angle of 90°. Each mixing element is laboriously welded from two groups consisting in each case of at least two rib sheets staggered in relation to each other and adjusted to fit the flow duct. The precise positioning of the ribs in relation to each other, so that each individual rib is arranged at an angle to the direction of flow, is particularly complicated and laborious, so that each mixer has to be produced-separately as a single unit. The plates employed do not have structured and non-structured regions, are not superimposed and do not extend over the entire flow duct width at right angles to the main flow stream.
EP 1 067 352 A1 describes a heat exchanger which has internal heating tubes in the main flow duct in order to provide an additional or larger heating surface in the flow region. The internal heating tubes additionally have, analogously to DE 3 022 270 C2 (=U.S. Pat. No. 4,352,318), sheet metal segments into which holes are bored and which are welded to the inner heating tubes. EP 1 067 352 A1 is therefore similar to DE 3 022 270 C2 (=U.S. Pat. No. 4,352,318), except for the additional internal temperature-adjusting tubes. In EP 1,067 352 A1 the inner heating tubes with the welded-on deflecting sheets can only be removed as a whole from the main flow duct.
FR 2 123 185 A1 describes a rectangular duct with an insertable plate. This insertable plate has to be cut, punched, the outer edges bent and the inner plate sections additionally deformed twice. In addition, no ribs are present which extend in particular over the width of the flow duct. No three-dimensional lattices can be identified, no contact lines and no contact points, and only contact surfaces. The same principle is described in GB 2 044 911 for circular ducts.
Finally, EP-A 1 213 556 describes flat tubes with several adjacently arranged flow regions which open into a collecting pipe. The flat tubes consist of several parallel flow ducts, so that the walls of the individual chambers have a pressure-stabilizing effect on the shape of the flat tube. Several flat tubes arranged in parallel, all of which open into a collecting pipe, form a heat exchanger. The shape of the flat tube described is obtained in an extrusion process using for example aluminium. The production of these flat tubes is complicated and special tools are required. As a result, such flat tubes cannot be produced from highly corrosion-resistant materials.
The problem therefore existed of developing a device and a process for improving processes for adjusting the temperature of single-phase and/or two-phase liquid or gaseous product streams and minimizing operational problems, such as for example fouling occurring inside the device. In addition a simple and effective cleansing method was required. This additional problem also involved modification of the flow duct, so that the turbulence generators or turbulence-producing elements had to be improved in conjunction with the flow duct containing them. The flow duct and the turbulence generators had to be simple to produce, so that production costs are low and an inexpensive new technology is obtained. The entire device must have a small, compact design in order to obtain additional advantages over the prior art. The temperature-adjusting performance of the flow ducts or tubes must be increased by elements which are as simple as possible to insert, so that, given an improved residence spectrum and a minimum volume of product in the temperature-adjusting duct, the temperature-adjusting performance is considerably increased. In addition, the improved temperature-adjusting performance must also be obtained for products having an increased viscosity of for example up to 100,000 mPas. This problem is particularly difficult since highly viscous products have laminar flow properties and the flow rates are kept low so as to minimize the pressure losses. Experts in the field refer to such low flow rates as creeping or crawling rates of flow. Due to the possible high losses in pressure, pressure stability of at least 300 bar must be obtained.
According to the invention, the above problem is solved by a housing (1), preferably according to
In a preferred embodiment of the invention the plates lie on top of and touch each other.
The combs can be straight or bent.
Several comb layers are therefore preferably superimposed above each other in such a manner that in relation to a first layer the next adjacent layer is rotated about its longitudinal axis by a degree of 180° so that the rotated layer forms an angle α′ (
The housing containing the comb-shaped plates which act as turbulence generators can be a tube or a shaped tube but in particular a rectangular duct or a flat duct.
In a preferred embodiment of the invention structured sections (4) in the form of ribs and gaps are formed on both sides of a non-structured section (3) and the ribs extend to the inner housing wall.
The housing according to the invention allows temperature-adjusting processes to be carried out efficiently and with low investment costs.
The present invention therefore also relates to a process for efficiently carrying out processes for adjusting the temperature of single-phase and/or two-phase liquid or gaseous product streams, characterized in that a housing (1) such as that depicted for example in
In order to obtain complete mixing over the entire flow cross-section of the housing complete packing with turbulence generators is preferred, so that at least two comb-shaped plates fill the free housing cross-section.
The processes for adjusting the temperature of single-phase and/or two-phase liquid or gaseous product streams using the housing containing turbulence generators according to the invention can be employed in a temperature range from about −100° C. to about 800° C. and they therefore have considerable advantages over the known prior art. In addition, they are suitable for substances with viscosities of from about 0.1 mPas to about 100,000 mPas. Due to the large volumetric flow rates and the large viscosity range, high differential pressures can be formed which can range from a few mbars to several hundred bars. The device according to the invention can therefore also be used for turbulent and laminar flow ranges as well as for creeping or crawling flow rates.
The soiling or fouling problems normally occurring frequently in industrial heat transfer processes are considerably reduced in the present process. The housing according to the invention can be cleaned efficiently and particularly simply, since the turbulence generators are designed to be insertable and removable.
Housings containing turbulence generators according to the invention are also particularly suitable for corrosive substances and mixtures of substances to be temperature-adjusted, since they can be produced inexpensively from high-quality, corrosion-resistant materials.
The invention therefore also relates in particular to heat exchangers whose tubes or housings are adapted to the turbulence generators according to the invention.
The turbulence-generating or turbulence-increasing elements according to the invention in the form of structured layers and packs of layers formed therefrom are used in particular to improve the temperature-adjusting performance of heat exchanger ducts with a rectangular shape. The use of the turbulence generators according to the invention in combination with filling elements increases the flow rate of the fluid while providing constant flow, so that economic use is also possible in circular duct cross-sections or tubes. The structured layers resemble combs but the teeth of the combs are arranged at an angle to the direction of flow.
It is also inventive for a turbulence generator to be designed in such a manner that structured sections (34, 3) in the form of ribs and gaps are formed on both sides of a non-structured section (3) (cf.
In a special embodiment the turbulence generator consists of three sections and has the shape of a double comb with ribs inclined in the direction of flow.
The structured sections of a double comb according to the invention which are in the form of ribs and gaps can vary so that, depending on the technical problem concerned the angle α, the length of the ribs and the distance between the ribs can be varied in order to provide optimum flow conditions for a particular temperature-adjusting process. In special cases the turbulence generators with structured sections on both sides can be designed in such a manner that one layer (comb-shaped plate) has different structured sections in the main direction of flow (cf.
The simple production-friendly design which allows variation of the structured sections by changing the position of the ribs, their angle, their width in the main direction of flow, the distance between the ribs and their shape, provides all degrees of freedom for designing the turbulence generators in an optimum process-engineering manner to suit the temperature adjustment problem concerned.
Packs of comb layers are simple to design since the thickness of the plates, the distances between the ribs, the length of the comb layers and the ratio between the widths of the structured and non-structured sections are readily variable. All process-engineering parameters necessary for a temperature adjustment process can be sufficiently taken into account. Since the turbulence generators can be inserted removably into temperature-adjusting ducts and a plurality of layers is always required, mass production is almost always possible in order to reduce piece costs.
The production of the turbulence generators according to the invention from plates or metal sheets always results in rib shapes having a square or rectangular cross-section. Square ribs arranged at an angle are particularly effective from the point of view of flow dynamics and increase turbulence particularly effectively. Particularly in the case of viscous fluids effective transverse mixing automatically occurs so that constant displacement of the substance to be temperature-adjusted from the inner heating surface to the centre of the flow duct takes place. This automatic displacement produces constant transverse mixing and prevents temperature peaks in the fluid. An additional advantage of the intense transverse mixing is reflected in the temperature-adjusting performance of the housing containing turbulence generators according to the invention, since in each perfused section of the temperature-adjusting duct the temperature equalization between the temperature-adjusting medium and the product takes place with a maximum average temperature difference. This means that the heat exchangers employed, in particular when a rectangular duct bundle heat exchanger is used, are shorter compared with known heat exchangers.
If the temperature-adjusting performance of very large flow ducts or cross-sections, such as for example housings of larger than 200 mm, is to be improved the comb-shaped turbulence generators according to the invention can have a hollow design produced from hollow sections, so as to considerably-reduce the weight of the comb layers required.
Heat exchange ducts with a rectangular cross-section have high potential for standardization and for the inexpensive mass production of heat exchangers since the problem-solving design is restricted to the structure of the comb layers or the packs of comb layers. This variant can be particularly advantageously used for motorcar radiators, coolers for oil-hydraulic equipment, exhaust gas coolers and flash heaters for the pharmaceutical or biotechnological industry.
Particularly the use of materials with high material-specific thermal conductivities and a simultaneously high product-side heat transfer surface and low hold-up in the temperature-adjusting duct favours non-product-damaging temperature adjustment. Even mixtures of fluids whose individual components have various densities can be effectively temperature-adjusted since constant complete mixing of the fluid stream in the duct fitted with comb layers is guaranteed and even the segregation of a two-phase substance mixture is prevented.
In the case of particularly sensitive biotechnological processes requiring a high degree of sterility, cleaning can be carried out particularly simply. Due to the low manufacturing costs it is possible, depending on the application concerned, to use the packs of comb layers as disposable inserts and to replace them for each new product or for each production series.
Thus, particularly in the pharmaceutical industry equipment combinations such as metallic rectangular duct bundle heat exchangers with comb layer packs produced for example from plastics, are particularly advantageous. The comb layers consisting of plastic can be produced very inexpensively in injection-moulding machines and the turbulence-generating or turbulence-increasing elements can be used as disposable insert kits without any major financial loss.
Applications where anti-corrosion requirements are particularly high and metallic materials cannot be used are therefore also economical. Rectangular duct bundle heat exchangers made of graphite or glass can be produced in a technically simple manner. In particular in the case of glass, which has low thermal conductivity, it is advantageous to use the turbulence generators according to the invention in order to be able to employ a maximum possible mean temperature difference at each point along the temperature-adjusting duct. If the temperature-adjusting tubes or ducts are made of a material with low thermal conductivity comb layers of plastics such as for example polytetrafluoroethylene, polypropylene or other thermoplastics can be advantageously used. In these applications the generation of turbulence takes place with only two layers and the housing is an extremely flat rectangular duct.
According to the invention, the structured plates or layers (2,2′) have a comb-shaped appearance, while having teeth which are inclined in the main direction of flow, and they can therefore also be referred to as comb plates or comb layers.
The layers are preferably plates whose largest width extension corresponds to the parallel distance between the directly opposing inner housing contact points in the flow cross-section of the housing. The comb layers are always in contact with the inner housing wall. A continuous contact line is always formed along the non-structured region of the comb and/or at least one broken contact line is formed along the structured region of the comb over the longitudinal extension of the housing. The longitudinal extension of the housing corresponds to its extension parallel to the main direction of flow.
At least two superimposed, assembled and inserted comb layers form a layered three-dimensional lattice in the flow region of the interior of the housing. This lattice extends particularly over the length of the duct.
According to the invention the width of the structured plates is preferably slightly larger than the equivalent width of the housing, in order to improve the metallic contact and the transfer of energy. If two identically structured plates with a slight excess width are superimposed and inserted into the temperature-adjusting housing the angle β varies compared with the angle α as a result of the elastic property of the inclined teeth of the combs. The structured plates are in a tensioned state after their insertion into the housing; they are, as it were, fixed by tension between the parallel points of contact in the interior of the housing, so that the inserted comb layers are prevented from slipping out as a result of the throughflow of the fluid and the resulting loss in pressure.
The length of the structured plates or comb layers acting as turbulence generators corresponds to several times the Width of the plates.
The structured comb plates can be produced from all types of metallic materials or alloys, non-metallic materials, plastics or possibly also from glass or ceramics, so that there are no limitations with regard to differing chemical anti-corrosion requirements. The structured comb plates are preferably produced from plates or metal sheets. Thus economical laser and etching processes can be used for their production. Additional economical production processes are punching, wire spark erosion, or, in the case of plate thicknesses of larger than 5 mm, casting processes can also be used. In a preferred variant the invention relates to turbulence generators and to housings containing same according to
The greater portion made up of the structured section of a turbulence generator is advantageous for the application concerned since optimum account can be taken of the product-specific and physical properties, such as for example the viscosity or varying densities or the resulting pressure loss.
In a further preferred embodiment the invention relates to housings (heat exchanger ducts) in which the cross-sectional throughflow area of the housing, tube, shaped tube or rectangular tube is packed with comb layers to an extent of 20% to 100%, preferably 30% to 100% and particularly preferably 50% to 100% of the free flow cross-section. In the case of a tube, the degree of filling is preferably 70-90%, and very particularly preferably 80%. In the case of shaped tubes the degree of filling is very preferably 80-95%, and very particularly preferably 90%, and in the case of rectangular tubes the degree of filling is very preferably 90-100% and very particularly preferably 100%.
In order to determine the degree of filling of the housing or the degree of filling of the cross-sectional flow area of a duct with comb layers, the cross-sectional area of the layers is calculated in relation to the cross-sectional inflow area of the duct. The proportion of the filled area formed by an individual layer is the product of the layer thickness and the layer width.
The degree of filling is the extent to which the individual flow duct is filled with the turbulence generators according to the invention. It is therefore advantageous to adjust the interior dimensions of the flow duct to the turbulence generators in order to as far as possible obtain a degree of filling of 100%.
If for example a circular flow duct or a tube is to be filled with comb layers, thus resulting in an increase in turbulence due to the higher flow rate and correspondingly improved temperature exchange between the temperature-adjusting chamber or zone and the fluid, the flow cross-section can be filled with layers. In order to fill a tube duct a large number of comb layers are stacked on top of each other. It can be advantageous for the user to fix several layers in the form of a pack of layers and to insert the pack as a whole. The formation of packs of layers simplifies insertion and removal.
The invention therefore also comprises fixing more than two layers underneath each other for the purposes of insertion, so that an assembled pack of layers can be inserted into or removed from the flow duct.
The fixing of several superimposed comb layers to each other can be carried out by localized welding or by the use of studs or screws or by soldering. Fixation must preferably be carried out in the non-structured section of the layers so that the ribs can be bent with a small amount of force for insertion into the housing.
The filling of circular flow ducts with comb layers according to the invention requires adjustment of the width of the turbulence generators to the inner contour of the housing in relation to their position therein. It is particularly simple to make adjustments when a pack of layers has been formed and this pack is adjusted to the contour of the housing by means of a grinding process.
If comb layers are inserted into shaped tubes and in particular into rectangular tubes (cf.
The present invention relates to housings in which for the constant reduction of the local temperature gradient the ribs of the comb layers are inclined at an angle α to the direction of flow over the length of a temperature-adjusting duct.
The ribs of the comb layers are preferably inclined at an angle α in the range from 20 to 80 degrees, preferably from 30 to 60 degrees and very preferably from 40 to 50 degrees to the direction of flow of the fluid, in order to form three-dimensional lattices over the entire throughflow length of the duct.
In an additional preferred embodiment the present invention relates to turbulence generators and housings containing same, in which the structured layers are characterized in that the width of the comb layers is larger than the inner linear distance between the parallel inner housing contact points, so that the rib angle β in the non-inserted state changes by less than 5 degrees during insertion and assumes the rib angle α, as a result of which the structured layers are always in contact with the inner wall of the housing after their insertion.
The maximum width extension of the comb layers in their non-inserted state is larger than their width in the inserted state. As a result, the selected rib angle β decreases to an angle α during insertion. The larger width extension of a comb layer means that during insertion the ribs bend elastically and the metallic contact with the inner temperature-adjusted housing wall is always guaranteed.
For this reason it is for example advantageous to design the ribs with a narrowed cross-section (cf.
In an additional preferred embodiment the present invention relates to housings in which the ribs of the comb layer have a preferred cross-sectional shape for bringing about an increase in turbulence and at the same time enhancing the radial and horizontal mixing effect of the ribs. The ribs of the layers then have cross-sectional shapes which are, for example, square, rectangular or hexagonal.
In an additional preferred embodiment the present invention relates to turbulence generators and housings containing same, in which the quotient of the plate thickness or the rib height and the rib width parallel to the direction of flow is preferably in the range from 0.1 to 5. Particularly preferably the quotient is in the range from 0.1 to 3.
The quotient of the rib thickness and the rib width ensures effective mixing action and an increase in turbulence during the flow through the duct filled with comb layers, even when substances having high viscosities, such as for example of 1 Pa to 10 Pas (pascals·second) are passed through and laminar flow occurs. At the same time temperature peaks are avoided over the entire length of the duct, thus also allowing temperature-sensitive substances to be temperature-adjusted in a non-damaging manner.
The distance between the centres of the ribs of the comb layers is therefore preferably greater than twice the rib width, and very preferably greater than four times the rib width and particularly preferably greater than five times the rib width of the comb layer.
The distance between the centres of the ribs affects the pressure loss occurring in a duct, and especially when substances with higher viscosities have to be temperature-adjusted it is advantageous to use a larger distance between the centres of the ribs in order to minimize the pressure loss.
In an additional preferred embodiment the present invention relates to turbulence generators and housings containing same, wherein the length of the comb layers or comb layer packs in the direction of flow is extended at one or both ends by an insertion flap, the total length of the layers or packs including the insertion flap being longer than the duct into which they are to be inserted, so that following insertion of the turbulence generators the insertion flaps project from the duct and additional fixation of the layers or layer packs outside the duct is possible.
The comb layers can have an additional insertion flap which is preferably arranged in the centre of the layer width and has an opening or hole. The opening can be used for the introduction of an insertion tool, so that a complete, non-fixed comb layer pack can be pulled into a duct. After the insertion the superimposed openings of the insertion flaps can be used for affixing an additional crossbar, such as a screw. Displacement of the layers during operation due to possibly occurring high losses in pressure is then no longer possible, since, in addition to the tensioned fixation of the layer ribs in the interior of the housing additional fixation outside the duct can for example be obtained by means of a protruding screw or a crossbar.
In an additional preferred embodiment the present invention relates to housings for use as turbulence generators, in which a flow duct is filled with a pack of layers and in which the pack of layers is composed of comb layers of varying thicknesses so as not only to increase turbulence and improve the mixing action but also to produce various flow rates over the flow cross-section and, due to the varying layer thicknesses, to simultaneously minimize the pressure loss.
Structured plates in the form of turbulence generators with various plate thicknesses can be combined to form packs of plates, so that the turbulence-increasing elements are removably inserted in the housing and are therefore simple to replace.
In an additional preferred embodiment the present invention relates to turbulence generators and housings containing same, wherein the length of a comb layer is at least as long as the duct into which it is to be inserted.
In this case the structured plates or comb layers have a length of 0.05 m to 5 m, preferably a length of 0.05 m to 2 m and particularly preferably a length of 0.05 m to 1 m so that they can be fabricated and inserted as far as possible in one piece.
In an additional preferred embodiment the present invention relates to turbulence generators with a double comb layer and housings containing same, wherein one comb layer has three sections and structured rib sections emanate from an inner, non-structured section.
Rib sections are understood to be the structured sections of a turbulence generator or comb layer according to the invention which are in the form of ribs and gaps.
Rib sections formed on both sides of a comb layer, which is thus referred to as a fish-bone layer or double comb layer, provide flow advantages since the fluid flows efficiently around all of the rib contact points on the temperature-adjusted inner duct walls and no dead zones and thus no product deposits occur. Product deposits on temperature-adjusted walls cause damage to and ageing of the product.
In an additional preferred embodiment the present invention relates to turbulence generators having a double comb layer (cf.
The different lengths of the structured sections mean in particular that comb ribs inclined at an identical angle α have different lengths. As a result, when a fluid flows through the duct containing double comb structures, such as for example a rectangular duct, different flow rate profiles are produced as a result of the pressure differences formed. These different flow rate profiles increase the mixing action and rapidly equalize local temperature differences. No duct regions occur which are ineffectively perfused, so that no dead spaces exist and product deposits are avoided.
Structured double comb layers consisting of three sections can be designed in such a manner that comb ribs of differing lengths emanate from the non-structured comb section. It can for example be advantageous for the section comprising long ribs to be inclined at a different angle to the main direction of flow than the section comprising short ribs.
In addition the long ribs can have different shapes (cf.
Structured layers having three sections, namely a non-structured section and two structured sections for forming the ribs and gaps can also be referred to as double comb elements or fish-bone structures.
The present invention does however also relate to turbulence generators having a double comb layer structure or single comb ribs and to housings containing same, in which, for example, if a circular flow duct cross-section is not completely filled, the non-filled flow cross-section is filled with filling elements (11) adapted to the cross-section and the filling elements then simultaneously serve as deflecting contours for guiding the flow, as shown for example in
The filling pieces or elements can be arranged on both sides or in an alternating fashion on a comb layer pack. Inner filling elements or deflecting devices in the form of staggered filling elements parallel to an inserted comb layer pack reduce pressure loss and produce high flow turbulence. At the same time transverse flow through the pack of comb layers is forcibly induced.
In an additional preferred embodiment the present invention relates to turbulence generators with single comb layers or with double comb layers and housings containing such turbulence generators, wherein the upstream and downstream faces of the filling elements (11) arranged on a pack of layers and employed for flow deflection form an angle γ to the central axis of the housing (see for example
The range of the angle γ of the upstream and downstream faces of the filling elements is preferably 20 to 70 degrees, very preferably 3.0 to 60 degrees and very particularly preferably 40 to 50 degrees.
In an additional preferred variant the present invention relates to turbulence generators having single comb layers or double comb layers and housings containing same, in which the deflecting elements are arranged opposite each other, i.e. above and beneath the comb layers or in an overlapping or staggered fashion in the direction of flow.
In an additional preferred variant the present invention relates to turbulence generators having a double comb layer or more than two comb layers and housings containing same, wherein at least two comb layers form a pack of comb layers and the comb layers or individual comb layers have structured zones or non-structured zones of different lengths in the direction of flow and as a result regions are formed over the entire duct length in the direction of flow which either increase turbulence or have steadied flow; see for example
Comb layers with variously structured zones also mean that the teeth of the combs in the various zones can be inclined at different angles to the main direction of flow and/or have different distances between the centres of the ribs.
As a result, depending on the requirements of the process concerned, it is possible to create different flow conditions with different temperature-adjusting capacities. Different zones of the comb layers in the direction of flow also mean that a pack of comb layers can be varied; layers with sections of comb teeth on one or both sides can be used, the distances between the centres of the teeth inserted can be varied over the length of the layers and the non-structured comb sections of the layers can be positioned centrically or eccentrically so that, for example, where a product of low viscosity flows through the housing, the flow conditions are not ordered but are almost forcibly chaotic.
The present invention also relates to turbulence generators and housings containing same, wherein the comb layers are soldered underneath each other at the contact points, thereby avoiding gaps in a comb layer pack and in particular in the overlapping region of the ribs.
The present invention does however also relate to turbulence generators and housings containing same, whose comb layers up to a layer thickness of less than 10 mm are preferably produced from metal sheets and preferably by laser, etching, wire erosion or water jet techniques.
Comb layers having a layer thickness of greater than 10 mm are preferably produced by casting. Comb layers produced by casting can be manufactured in one solid piece or in one hollow piece in order to save material and reduce weight.
The present invention also relates to turbulence generators and housings containing same, in which the comb layer elements and packs are used for increasing turbulence in catalytic processes and consist of structured layers comprising three sections, wherein the surfaces of the layers are completely coated with a catalyst material. The catalyst material which can be used can be any type of commonly used catalyst such as for example heterogeneous or homogeneous catalysts.
The present invention also relates to turbulence generators and housings containing same, wherein the comb layer elements and packs are used for increasing turbulence in catalytic processes and consist of structured sections, wherein the gaps are filled with catalyst granules or with coated ceramic catalyst supports.
The present invention does however also relate to turbulence generators and housings containing same, wherein an arrangement of comb layer packs and insertion flaps at both ends is arranged in such a manner that at least two comb layer packs are connected in succession by a coupling connection and they fill out the entire length of a temperature-adjusting duct.
The arrangement of at least two comb layer packs in succession in a flow duct forms a chain of comb layer packs.
Chains of comb layer packs, so-called comb layer chains, can also be inserted in non-linear temperature-adjusted ducts, tubes or shaped tubes if the connecting elements or coupling connections have swivel joints.
The present invention does however also relate to turbulence generators and housings containing same in which the comb layer packs arranged in chain-like succession have a preferred length of 50 mm to 200 mm and particularly preferably a length of 50 mm to 100 mm.
The present invention also relates to turbulence generators and housings containing same, wherein the comb layer packs arranged in chain-like succession and combined with filling elements are rotated by 70 to 100 degrees and preferably 75 to 95 degrees in relation to each other for use in ducts and are movably connected to each other by assembly flaps.
The present invention does however also relate to heat exchangers of the kind depicted for example in
The total flow duct volume can be calculated from the volume of all of the perfused product ducts of the bundle heat exchanger without turbulence generators. Hold-up is understood to be the product volume accommodated in a duct packed with turbulence generators.
The rectangular duct bundle heat exchanger comprises at least two rectangular or slot-shaped ducts which are perfused in parallel and which have identical or different duct cross-sections and are packed with turbulence generators according to the invention. The ducts have joint larger inflow and outflow plates and a joint temperature-adjusting chamber. The hold-up and the residence time behaviour in the ducts of the fluid to be temperature-adjusted can be optimized by the packing of the slot-shaped ducts with turbulence generators. By the appropriate choice of the structures of the comb layers the pressure loss which occurs can also be varied, so that a high-performance heat exchanger can be produced with low investment costs.
Due to the geometrically variable comb layer or double comb layer structure the pressure loss can be varied over wide ranges so that heat exchangers for viscous fluids can be produced with a pressure loss of less than 100 bars, preferably less than 50 bars and particularly preferably less than 10 bars.
The residence time and the residence time behaviour in the temperature control duct are crucially important for non-product-damaging temperature adjustment so that, given an almost identical residence time behaviour in all of the parallel flow channels the temperature adjustment time can be simultaneously reduced by the appropriate choice of the comb layer structures. The uniform short temperature adjustment time is determined inter alia by the hold-up and the available heat exchange surface area, so that the rectangular ducts containing comb layer packs have an advantageous reduced total duct volume.
As already stated, the present invention also relates to a process for efficiently performing processes for adjusting the temperature of single-phase and/or two-phase liquid or gaseous product streams, characterized in that a turbulence generator according to the present invention is used.
The invention preferably relates to a temperature-adjusting process using the comb layer structures according to the invention and the rectangular duct heat exchanger according to the invention for the rapid temperature adjustment of a fluid or a fluid mixture, characterized in that the substances to be temperature-adjusted have a viscosity range from 0.001 to 1 Pas, preferably a viscosity of 0.1 mPas to 5,000 mPas and particularly preferably a product-specific viscosity of 0.1 mPas to less than 10,000 mPas, so that, due to the short residence time as a result of the small volume of the substance to be temperature-adjusted in the heat exchanger duct (hold-up) and due to the narrow residence time spectrum and the efficient transverse mixing in the flow duct, a temperature difference between the temperature-adjusting medium and the product outflow temperature is established in the outflow region of the slot-shaped ducts which is in the range from 2 to 20° C., preferably from 2 to 10° C. and particularly preferably from 2 to 5° C.
Particularly preferably the present invention relates to a process for efficiently adjusting the temperature of single-phase and/or two-phase liquid or gaseous product streams for performing endothermic or exothermic reactions with fluids in a single-phase or multi-phase state and to the use of a housing according to the invention as a tube reactor connected downstream of a mixer for the initial homogenization of the reactants upstream of one or more slot-shaped heat exchangers arranged successively in series or parallel to each other, so that the chemical reaction which begins after the passage through the mixer can be directly subjected to intense temperature adjustment in the slot-shaped ducts containing turbulence generators and the high mixing quality produced in the preliminary mixer is maintained in the slot-shaped duct during the course of the reaction.
Finally, the present invention relates to the use of the turbulence generators according to the invention preferably with corresponding rectangular ducts as flash heaters or as cross-current heat exchangers for the food industry, as sterilizers for pharmaceutical or biological processes, as off-gas coolers for the complete condensation of vapours and for the retention of valuable products in an off-gas stream for avoiding environmentally contaminating emissions, and in addition as heat exchangers for motorcar radiators or as oil coolers without a joint temperature-adjusting chamber, wherein the discharge of the heat quantity takes place via the external surface of the rectangular ducts to the ambient air and the performance of the cooler is increased by increasing the external surface areas of the rectangular ducts by affixing or soldering on sheet lamellae and effective heat discharge takes place to the ambient air, and, in a preferred variant, the use as motorcar radiators or oil coolers, characterized in that the coolers are produced from a material having a specific thermal capacity of 15 W/mK to 400 W/mK.
b depicts two superimposed layer-shaped comb structures in a housing, similar to
a depicts a plate section having a comb structure,
a depicts the circular flow cross-section of a tube with a layer pack and filling elements,
aa depicts the structured and unstructured sections in
b depicts a flow tube having filling elements in a staggered position in relation to each other in the direction of flow,
a depicts a double comb plate with short ribs and long ribs having a zigzag shape,
a depicts the cross-section of an individual motorcar radiator tube with externally fitted lamellae for the efficient discharge of heat into the air.
In
b depicts the housing (1) with the inserted structured plate (2) from
The structured plates can also be superimposed upon each other in such a manner that the non-structured comb sections are arranged in an alternating fashion in relation to the next adjacent layer, i.e. on the opposite side.
By way of comparison,
b depicts a circular tube or housing (1) which is packed with turbulence generators according to the invention in the form of a turbulence generator pack (12) and filling elements (11, 11′) are arranged at the top and at the bottom in a staggered fashion in the direction of flow (5).
The structured double comb element is provided with an eccentric, non-structured section (30) from which the teeth of the comb or the ribs (31, 32) extend on both sides up to the inner wall of the housing at an angle to the main direction of flow (5) of the fluid. The teeth (31) of the comb are shorter than the opposing comb teeth (32). The assembly to form a comb layer pack with ribs of a different length on both sides—also referred to as a double comb layer—means that the non-structured layer regions no longer lie on top of each other after the assembly of the pack. It is advantageous that the flow region does not have any dead areas in which substances can be deposited.
As a result, varying flow rate profiles can be established in the flow cross-section of the duct.
In addition, various three-dimensional lattice structures can be formed layer-wise in very wide shaped ducts or housings (rectangular ducts).
In order to facilitate insertion, the double comb layers are approximately as long as the flow duct itself and provided on both sides with an insertion flap (52, 52′). Using the insertion flap a complete double comb layer pack consisting of at least two structured layers can be inserted in a simple manner and optionally additionally secured against slipping by a screw or a bolt not illustrated in this figure. The temperature-adjusting chamber is not shown in
The slot-shaped duct bundle heat exchanger is not depicted in full length. It is possible for corresponding deflecting plates to be provided on the temperature-adjusting side.
Several flat ducts (71) according to the invention are completely filled with three turbulence generators (72) according to the invention. In addition, the flat ducts have external soldered-on lamellae (73) to allow the heat produced to be rapidly discharged to the surrounding air via the enlarged external surface of the flat duct. The flat ducts are inserted at both ends into collecting ducts (74, 75) and welded or soldered. When using materials having a high thermal conductivity coefficient, such as for example aluminium or copper, motorcar radiators can be constructed in this manner, the connecting points filled with a soldering metal and the radiator soldered as a whole.
a depicts an individual motorcar radiator tube in a sectional diagram. It can be seen that the flat duct (71) is filled with three turbulence generators according to the invention and completely fills the flow cross-section of the flat duct. The comb layers employed can be clearly seen and in particular the non-structured section (72′) and the structured section (72) in the form of ribs and gaps: A lamella (73) is depicted by way of illustration around the flat duct, which enlarges the external temperature-adjusting surface of the flat duct. In the figure part of the collecting duct (75) can also be seen.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10326381.0 | Jun 2003 | DE | national |
